WASHINGTON — Janet Napolitano is leaving her job as head of Homeland Security, and Sen. Charles Schumer is pushing President Obama to replace her with NYPD boss Ray Kelly.

Napolitano, the former Arizona governor, is leaving to run the sprawling University of California system, the Obama administration announced yesterday.

Almost immediately, Schumer — a powerhouse on immigration issues who met with Obama the day before the announcement — trumpeted his support for Kelly.

Schumer even called Obama’s chief of staff, Dennis McDonough, to make a pitch.

The agency’s leader “needs to be someone who knows law enforcement, understands anti-terrorism efforts, and is a top-notch administrator, and at the NYPD Ray Kelly has proven that he excels in all three,” Schumer said.

Schumer spoke to Kelly yesterday morning, hours before sending out a release calling the NYPD leader “the man for the job,” a Schumer aide told The Post.

That would indicate that Kelly had a chance to shoot down speculation as a possible Napolitano successor and didn’t.

Kelly did not immediately respond to requests for comment.

Schumer has floated Kelly’s name before for FBI director.

Kelly has resisted entreaties from top Republicans to run for mayor this year, and on Thursday said he will not run for any elected office.

White House press secretary Jay Carney, asked about Schumer’s pitch, said it was “far too premature” to speculate on a successor to Napolitano.

Kelly is a popular figure who once ran the border patrol under President Clinton and oversaw enforcement agents at the Treasury Department.

He has strong bipartisan relationships that could help him get through the Senate, where the two parties are at war over confirmations.

“Opposing a guy who has thwarted 16 terror attacks [in New York] is a tough thing to do,” said one Senate insider, who predicted that the only potential difficulties for Kelly might be the NYPD’s “stop-and-frisk” methods and surveillance of Muslim communities.

Bernard Kerik, the last police commissioner up for the Homeland Security job, had to bow out after President George W. Bush nominated him and a range of misdeeds surfaced during the vetting process.

Napolitano sometimes drew the ire of conservatives, getting mocked by the Drudge Report web site over government intrusions as “Big Sis.”

“Whoever replaces Secretary Napolitano must restore the rule of law, as well as the morale of [immigration] officers which has plummeted under her tenure,” said Sen. Jeff Sessions (R-Ala.), who fumed about her enforcement of the administration’s nondeportation orders.

“Now is a good time for Congress to consider dismantling the monstrous Department of Homeland Security and replacing it with a smaller security-focused entity that is realistically capable of connecting the dots of threats posed to our national security,” said Rep. John Mica (R-Fla.).

As The Post reported last summer, Napolitano first said she was considering stepping down after a top-ranking immigration aide left the agency following salacious accusations of a hostile work environment toward men.